Controlled release compositions comprising a combination of isosorbide dinitrate and hydralazine hydrochloride

ABSTRACT

The invention relates to a controlled release composition comprising a combination of isosorbide dinitrate and hydralazine, such as hydralazine hydrochloride, that in operation delivers the drug in a pulsed or multi-modal manner for the treatment of angina, ischaemic heart disease, arterial hypertension and related disease conditions. Preferably, the isosorbide dinitrate and hydralazine hydrochloride can be released from the dosage form in an erodable, diffusion and/or osmotic-controlled release profile.

FIELD OF INVENTION

The present invention relates to novel compositions for the treatment ofpatients suffering from angina, ischaemic heart disease, arterialhypertension and related disease conditions. In particular, the presentinvention relates to novel dosage forms for the controlled delivery ofcombinations of isosorbide dinitrate and hydralazine, or a salt orderivative thereof, and methods of treatment using the same.

BACKGROUND OF INVENTION

Isosorbide Dinitrate, classified as a vasodilator, anti-anginalcompound, is chemically known as 1,4:3,6-dianhydro-D-glucitol dinitrate;1,4:3,6-dianhydrosorbitol 2,5-dinitrate; dinitrosorbide; sorbidedinitrate; and sorbide nitrate. It has a CAS number of 87-33-2.Isosorbide dinitrate has a chemical formula of C₆H₈N₂O₈, and a molecularweight of 236.1.

The chemical structure of isosorbide dinitrate is shown below:

Isosorbide dinitrate is a fine white to ivory-white odorless crystallinesolid. It is sparingly soluble in water (1.0 g/900 ml); freely solublein acetone, chloroform, alcohol and ether, and has a melting point of70° C. Isosorbide dinitrate is a synthetic substance prepared fromsorbitol. Diluted isosorbide dinitrate is a mixture of isosorbidedinitrate (usually 20-50%) with lactose, mannitol, or excipients addedto minimize the risk of explosion. It may contain up to about 1% of asuitable stabilizer such as ammonium phosphate.

Isosorbide dinitrate is commercially available, for example, under thetrade names DILATRATE®-SR (Schwarz Pharma, Milwaukee, Wis.); ISORDIL®and ISORDILR TITRADOSE® (Wyeth Laboratories Inc., Philadelphia, Pa.);and SORBITRATE® (Zeneca Pharmaceuticals, Wilmington, Del.). Isosorbidedinitrate is also commercially available under such trade names asCedocard-5, Cedocard-10, Cedocard-20, Cedocard Retard, Cedocard IV(Tillotts, UK), Isoket, Isoket 10, Isoket 20, Isoket Retard, Isoket 0.1%(Schwartz, UK), Isordil, Isordil Tembids (Ayerst, UK), Sorbichew,Sorbitrate (Stuart, UK), Vascardin (Nicholas, UK), Soni-Slo (Lipha Rona,UK); Conducil, Corosorbide, Maycor, Sigillum, Surantol, Vasodilat(Argentina); Carvasin, Isotrate (Australia); Sorbidilat (Belgium);Coronex (Canada); Risordan (France); Cardis, Corovliss, IsoMack, Maycor,Nitrol, Nitrosorbon, Sorbidilat, Vermicet (Germany); Carvasin,Nitrosorbide, (Italy); Directan, Nitrol (Japan); Isorbid (Mexico);Sorbaugil (Norway, Sweeden); IsoMack, Myorexon, Sorbidilat(Switzerland); Iso-Bid, Iso-D, Isotrate, Sorbide, Sorquad, Vasotrate(USA).

Isosorbide dinitrate is used principally for management of ischaemicheart disease by reducing the number, duration and severity of episodesof angina pectoris. It is effective for angina (e.g., stable effortangina, mixed angina, unstable angina and vasospastic or variantangina). Isosorbide dinitrate is used in acute myocardial infarction incontrol of ischaemic pain, reduction of elevated blood pressure and inthe treatment of pulmonary edema and congestive cardiac failure. It isalso useful in the treatment of severe hypertension.

Therapeutic isosorbide dinitrate dosages for adults for relief of acuteattacks of angina, generally range from about 2.5 mg to about 10 mg. Forlong term management of ischaemic heart disease dosing ranges from about30 mg to about 240 mg per day. Starting doses for the treatment ofangina pectoris may be about 2.5 mg to about 10 mg every 2 to 3 hours,with dosages gradually increased up to about 10 mg to about 40 mg every6 hours.

Hydralazine (including its salts, such as hydralazine hydrochloride) isclassified as a vasodilator, antihypertensive compound. Hydralazine,also known as 1-hydrazinophatalazine; has a CAS number of 86-54-4.Hydralazine hydrochloride, also known as 1-hydrazinophtalazinehydrochloride; has a CAS number of 304-20-1. Hydralazine has thechemical structure of C₈H₈N₄, and hydralazine hydrochloride has thechemical structure of C₈H₈N₄.HCl.

The chemical formula of hydralazine and hydralazine hydrochloride areshown below:

Hydralazine hydrochloride has a white to off-white substance color andis a crystalline powder. It is an odorless to almost odorless compound.It is soluble in water (1 in 25), slightly soluble in ethanol (1 in 500)and in methanol; practically insoluble in ether or chloroform. A 2%solution in water has a pH of about 3.5 to about 4.2.

Hydralazine hydrochloride is commercially available from, for example,Lederle Standard Products of Pearl River, N.Y. and Par PharmaceuticalsInc. of Spring Valley, N.Y. Hydralazine hydrochloride is branded underseveral trade names, such as Alphapress, Apresolin, Apresolina,Apresoline, Dralzine, Hidralazina, Hydralazine Hydrochloride Tablets USP23, Hydralazine Injection BP 1993, Hydralazine Tablets BP 1993,Hydrapress, Hyperphen, Ipolina, Lowpress, Nepresol, Novo-Hylazin,Rolazine, Slow-Apresoline, and Supress.

Hydralazine, including its pharmaceutically acceptable salt forms, e.g.,hydralazine hydrochloride, is useful in the treatment of arterialhypertension (primary; malignant; pulmonary; pre-eclampsia andeclampsia), congestive heart failure, pulmonary hypertension in chronicobstructive pulmonary disease, and aortic regurgitation. Therapeuticdosages for adults range generally from about 10 mg four times a day forthe first 2 to 4 days, increasing to about 25 mg 4 times a day for theremainder of the first week. For the subsequent weeks, dosages may beincreased up to about 50 mg 4 times a day. For heart failure dosages mayrange up to about 800 mg daily or more.

Isosorbide dinitrate and hydralazine hydrochloride combinations, and/orlike compounds, have been disclosed, for example, in U.S. Pat. No.4,868,179 to Cohn for “Method of Reducing Mortality Associated withCongestive Heart Failure Using Hydralazine and Isosorbide Dinitrate”;U.S. Pat. No. 6,465,463 to Cohn et al. for “Methods of Treating andPreventing Congestive Heart Failure with Hydralazine Compounds andIsosorbide Dinitrate or Isosorbide Mononitrate”; U.S. Pat. No. 6,635,273to Loscalzo et al. for “Methods of Treating Vascular DiseasesCharacterized by Nitric Oxide Insufficiency”; and United States PatentApplication No. 2004/0204371 to Cohn et al. for “Kits of HydralazineCompounds and Isosorbide Dintrate and/or Isosorbide Mononitrate”.

The combination of isosorbide dinitrate and hydralazine hydrochloridehas been developed by Nitromed, Inc. of Lexington, Mass. under the tradename BiDil®. The combination has been reported to provide a synergistictherapeutic effect for patients over the individual use of each of theactive agents. BiDil® is generally administered three times a day indosages of isosorbide dinitrate/hydralazine hydrochloride, respectivelyfrom about 60/112.5 to about 120/225 mg.

The present invention relates to a composition for thecontrolled-release of a combination of isosorbide, including salts,derivatives and metabolites thereof, such as isosorbide dinitrate,(referred to herein as “isosorbide dinitrate”) and hydralazine, or saltor derivative thereof, such as hydralazine hydrochloride (referred toherein as “hydralazine hydrochloride”). In particular, the presentinvention relates to a composition that in operation delivers an activeisosorbide dinitrate and hydralazine hydrochloride combination in apulsatile or in a constant zero order release manner. The presentinvention further relates to solid oral dosage forms containing such acontrolled release composition. The present invention is particularlyapplicable for multiparticulate formulations of a combination productfor isosorbide dinitrate and hydralazine hydrochloride, providing atwice-a-day or once daily administration. In particular, the presentinvention provides immediate-release pellets and/or beads for isosorbidedinitrate and hydralazine hydrochloride, e.g., using powder layeringtechnology or standard Glatt Wurster Process, and sustained-releasepellets and/or beads for isosorbide dinitrate and hydralazinehydrochloride, e.g., using various polymers or combination of polymersto provide various release rates ranging from about 6 hours to about 12hours or about 12 hours to about 24 hours with or without lag time. Inone particularly preferred embodiment, these multiparticulates areencapsulated in a hard gelatin capsule to give an isosorbide dinitratecontent of about 30 mg to about 120 mg and a hydralazine content ofabout 50 mg to about 250 mg ranging for about 12 hour to about 24 hourdosing. Representative proportions of the immediate release (IR) beadsvary from about 10% to about 60%, with representative proportions ofcomplementary sustained release (SR) beads varying from about 30% toabout 90%. The IR/SR combination may be blended for ease of manufactureor may be individually dosed with capsules. Additionally, themultiparticulates manufactured can be tabletted using suitableexcipients to give appropriate isosorbide dinitrate and hydralazinecontent, as stated above.

DESCRIPTION OF THE INVENTION

The plasma profile associated with the administration of a drug compoundmay be described as a “pulsatile profile” in which pulses of highisosorbide dinitrate and hydralazine hydrochloride concentration,interspersed with low concentration troughs, are observed. A pulsatileprofile containing two peaks may be described as “bimodal”. A pulsatileprofile containing two or more peaks may be described as “multi-modal”.Similarly, a composition or a dosage form which produces such a profileupon administration may be said to exhibit “pulsed release” of theisosorbide dinitrate and hydralazine hydrochloride.

Conventional frequent dosage regimes in which an immediate release (IR)dosage form is administered at periodic intervals typically gives riseto a pulsatile plasma profile. In this case, a peak in the plasma drugconcentration is observed after administration of each IR dose withtroughs (regions of low drug concentration) developing betweenconsecutive administration time points. Such dosage regimes (and theirresultant pulsatile plasma profiles) have particular pharmacological andtherapeutic effects associated with them. For example, the wash outperiod provided by the fall off of the plasma concentration of theactive between peaks has been thought to be a contributing factor inreducing or preventing patient tolerance to various types of drugs.

Multiparticulate modified controlled release compositions similar tothose disclosed herein are disclosed and claimed in the U.S. Pat. Nos.6,228,398 and 6,730,325 to Devane et al; both of which are incorporatedby reference herein. Additional disclosures of a spheroidal oral drugabsorption system for multiparticulate drug delivery for controlling therelease and absorption rate of particular active agents are found inU.S. Pat. No. 4,863,742 to Panoz et al.; U.S. Pat. No. 4,917,899 toGeoghegan et al.; and U.S. Pat. No. 6,066,339 Stark et al., thedisclosures of which are herein incorporated by reference. Typicallythis spheroidal oral drug absorption system includes microshperoidalbeads having representative diameters of from about 0.5 mm to about 2.0mm, with each bead providing a miniature controlled absorption system,allowing individualized release rates for the isosorbide dinitrate andhydralazine hydrochloride. Such beads may be dispensed in dispensingsystems, such as capsules, sprinkles and tablets.

Accordingly, it is an object of the present invention to provide amultiparticulate modified release composition containing isosorbidedinitrate and hydralazine hydrochloride which in operation produces aplasma profile substantially similar to the plasma profile produced bythe administration of three or more IR dosage forms given sequentially.

It is a further object of the invention to provide a multiparticulatemodified release composition which in operation delivers isosorbidedinitrate and hydralazine hydrochloride in a pulsatile manner.

Another object of the invention is to provide a multiparticulatemodified release composition which substantially mimics thepharmacological and therapeutic effects produced by the administrationof three or more IR dosage forms given sequentially.

Another object of the present invention is to provide a multiparticulatemodified release composition which substantially reduces or eliminatesthe development of patient tolerance to isosorbide dinitrate andhydralazine hydrochloride of the composition.

Another object of the invention is to provide a multiparticulatemodified release composition in which a first portion of an isosorbidedinitrate and hydralazine hydrochloride combination is releasedimmediately upon administration and a second portion of the activeingredient is released rapidly after an initial delay period in amulti-modal manner.

Another object of the present invention is to formulate the dosage formsas erodable formulations, diffusion-controlled formulations, andosmotic-controlled formulations that deliver the drug in a zero orderfashion for about 12 to about 24 hours.

Another object of the invention is to provide a multiparticulatemodified release composition capable of releasing isosorbide dinitrateand hydralazine hydrochloride in a bimodal or multi-modal manner inwhich a first portion of the active is released either immediately orafter a delay time to provide a pulse of drug release and one or moreadditional portions of the active are released each after a respectivelag time to provide additional pulses of drug release.

Another object of the invention is to provide solid oral dosage formscomprising a multiparticulate modified release composition of thepresent invention.

Other objects of the invention include provision of a once daily dosageform of an isosorbide dinitrate and hydralazine hydrochloride which, inoperation, produces a plasma profile substantially similar to the plasmaprofile produced by the administration of three immediate release dosageforms given sequentially and a method for treatment of angina, ischaemicheart disease, arterial hypertension and related disease conditionsbased on the administration of such a dosage form.

DETAILED DESCRIPTION OF THE INVENTION A. Multiparticulate ControlledRelease Isosorbide Dinitrate and Hydralazine Hydrochloride Compositions

The above objects are realized by a controlled release compositionhaving a first component comprising a first population of isosorbidedinitrate and hydralazine hydrochloride, and a second and subsequentcomponent comprising a second and subsequent population of isosorbidedinitrate and hydralazine hydrochloride particles. Theingredient-containing particles of the second and subsequent componentare coated with a modified release coating. Alternatively oradditionally, the second and subsequent population of isosorbidedinitrate and hydralazine hydrochloride-containing particles furthercomprises a modified release matrix material. Following oral delivery,the composition in operation delivers the isosorbide dinitrate andhydralazine hydrochloride in a first order (pulsatile) or zero ordermanner.

In a preferred embodiment, the controlled release composition of thepresent invention comprises a first component which is an immediaterelease component.

The modified release coating applied to the second and subsequentpopulation of isosorbide dinitrate and hydralazine hydrochloride causesa lag time between the release of active from the first population ofactive isosorbide dinitrate and hydralazine hydrochloride-containingparticles and the release of active from the second and subsequentpopulation of active isosorbide dinitrate and hydralazinehydrochloride-containing particles. Similarly, the presence of amodified release matrix material in the second and subsequentpopulations of active isosorbide dinitrate and hydralazinehydrochloride-containing particles causes a lag time between the releaseof isosorbide dinitrate and hydralazine hydrochloride from the firstpopulation of isosorbide dinitrate and hydralazinehydrochloride-containing particles and the release of active ingredientfrom the second population of active ingredient containing particles.Similarly, the presence of a modified release matrix material in thesecond and subsequent population of active isosorbide dinitrate andhydralazine hydrochloride-containing particles causes a lag time betweenthe release of isosorbide dinitrate and hydralazine hydrochloride fromthe second population of isosorbide dinitrate and hydralazinehydrochloride-containing particles and the release of active ingredientfrom the third population of active ingredient containing particles. Theduration of the lag time may be varied by altering the compositionand/or the amount of the modified release coating and/or altering thecomposition and/or amount of modified release matrix material utilized.Thus, the duration of the lag time can be designed to mimic a desiredplasma profile.

Because the plasma profile produced by the controlled releasecomposition upon administration is substantially similar to the plasmaprofile produced by the administration of two or more IR dosage formsgiven sequentially, the controlled release composition of the presentinvention is particularly useful for administering isosorbide dinitrateand hydralazine hydrochloride for which patient tolerance may beproblematical. This controlled release composition is thereforeadvantageous for reducing or minimizing the development of patienttolerance to the active ingredient in the composition.

In a preferred embodiment of the present invention, isosorbide dinitrateand hydralazine hydrochloride and the composition in operation deliversthe isosorbide dinitrate and hydralazine hydrochloride in a multi-modalpulsatile or zero order manner. Such a pulsatile composition inoperation produces a plasma profile which substantially mimics thatobtained by the sequential administration of two IR doses as, forinstance, that found in a typical treatment regimen. The presentinvention further relates to a controlled release composition comprisingisosorbide dinitrate and hydralazine hydrochloride which in operationproduced a plasma profile that eliminates the “peaks” and “troughs”produced by the administration of two or more IR dosage forms givensequentially if such a profile is beneficial. This type of profile canbe obtained using a controlled release mechanism that allows for“zero-order” delivery.

The present invention also provides solid oral dosage forms comprisingthe novel compositions of the present invention.

The term “particulate” as used herein refers to a state of matter whichis characterized by the presence of discrete particles, pellets, beadsor granules irrespective of their size, shape or morphology. The term“multiparticulate” as used herein means a plurality of discrete oraggregated particles, pellets, beads, granules or mixture thereof,irrespective of their size, shape or morphology.

The term “modified release” as used herein with respect to the coatingor coating material or used in any other context, means release which isnot immediate release and is taken to encompass controlled release,sustained release and delayed release.

The term “time delay” as used herein refers to the duration of timebetween administration of the composition and the release of theisosorbide dinitrate and hydralazine hydrochloride from a particularcomponent.

The term “lag time” as used herein refers to the time between deliveryof the isosorbide dinitrate and hydralazine hydrochloride from onecomponent and the subsequent delivery isosorbide dinitrate andhydralazine hydrochloride from another component.

The term “erodable” as used herein refers to formulations which may beworn away, diminished, or deteriorated by the action of substanceswithin the body.

The term “diffusion controlled” as used herein refers to formulationswhich may spread as the result of their spontaneous movement, forexample, from a region of higher to one of lower concentration.

The term “osmotic controlled” as used herein refers to formulationswhich may spread as the result of their movement through asemi-permeable membrane into a solution of higher concentration thattends to equalize the concentrations of the formulation on the two sidesof the membrane.

The active ingredient in each component may be the same or different.For example, a composition may comprise a first component containingisosorbide dinitrate and hydralazine hydrochloride, and the secondcomponent may comprise a second active ingredient which would bedesirable for combination therapies. Indeed, two or more activeingredients may be incorporated into the same component when the activeingredients are compatible with each other. A drug compound present inone component of the composition may be accompanied by, for example, anenhancer compound or a sensitizer compound in another component of thecomposition, in order to modify the bioavailability or therapeuticeffect of the drug compound.

As used herein, the term “enhancer” refers to a compound which iscapable of enhancing the absorption and/or bioavailability of an activeingredient by promoting net transport across the GIT in an animal, suchas a human. Enhancers include but are not limited to medium chain fattyacids; salts, esters, ethers and derivatives thereof, includingglycerides and triglycerides; non-ionic surfactants such as those thatcan be prepared by reacting ethylene oxide with a fatty acid, a fattyalcohol, an alkylphenol or a sorbitan or glycerol fatty acid ester;cytochrome P450 inhibitors, P-glycoprotein inhibitors and the like; andmixtures of two or more of these agents.

Furthermore, as stated herein, “stabilizers” refers to a compound whichis capable of enhancing the stability of an active ingredient e.g.stability enhancers, pH modifiers, chelating agents, antioxidants, freeradical sequestrants, etc. . . . Examples of stabilizers include but arenot limited to edetic acid and salts thereof, citric acid and saltsthereof, and ascorbic acid, fumaric acid and salts thereof.

The proportion of the isosorbide dinitrate and hydralazine hydrochloridecontained in each component may be the same or different depending onthe desired dosing regime. The isosorbide dinitrate and hydralazinehydrochloride are present in the first component and in the secondcomponent in any amount sufficient to elicit a therapeutic response. Theisosorbide dinitrate and hydralazine hydrochloride, when applicable, maybe present either in the form of one substantially optically pureenantiomer or as a mixture, racemic or otherwise, of enantiomers. Theisosorbide dinitrate and hydralazine hydrochloride are preferablypresent individually in a composition in an amount of from about 0.1 toabout 500 mg, preferably in the amount of from about 1 about 100 mg. Theisosorbide dinitrate and hydralazine hydrochloride are each preferablypresent in the first component in an amount of from about 0.5 to about60 mg; more preferably the isosorbide dinitrate and hydralazinehydrochloride are each present in the first component in an amount offrom about 2.5 to about 30 mg. The isosorbide dinitrate and hydralazinehydrochloride are present in the subsequent components in an amountwithin a similar range to that described for the first component.

The time release characteristics for the delivery of the isosorbidedinitrate and hydralazine hydrochloride from each of the components maybe varied by modifying the composition of each component, includingmodifying any of the excipients or coatings which may be present. Inparticular, the release of the isosorbide dinitrate and hydralazinehydrochloride may be controlled by changing the composition and/or theamount of the modified release coating on the particles, if such acoating is present. If more than one modified release component ispresent, the modified release coating for each of these components maybe the same or different. Similarly, when modified release isfacilitated by the inclusion of a modified release matrix material,release of the active ingredient may be controlled by the choice andamount of modified release matrix material utilized. The modifiedrelease coating may be present, in each component, in any amount that issufficient to yield the desired delay time for each particularcomponent. The modified release coating may be preset, in eachcomponent, in any amount that is sufficient to yield the desired timelag between components.

The lag time or delay time for the release of the isosorbide dinitrateand hydralazine hydrochloride from each component may also be varied bymodifying the composition of each of the components, including modifyingany excipients and coatings which may be present. For example, the firstcomponent may be an immediate release component wherein the isosorbidedinitrate and hydralazine hydrochloride are released immediately uponadministration. Alternatively, the first component may be, for example,a time-delayed immediate release component in which the isosorbidedinitrate and hydralazine hydrochloride are released substantially intheir entirety immediately after a time delay. The second and subsequentcomponent may be, for example, a time-delayed immediate releasecomponent as just described or, alternatively, a time-delayed sustainedrelease or extended release component in which the isosorbide dinitrateand hydralazine hydrochloride are released in a controlled fashion overan extended period of time.

As will be appreciated by those skilled in the art, the exact nature ofthe plasma concentration curve will be influenced by the combination ofall of these factors just described. In particular, the lag time betweenthe delivery (and thus also the on-set of action) of the isosorbidedinitrate and hydralazine hydrochloride in each component may becontrolled by varying the composition and coating (if present) of eachof the components. Thus by variation of the composition of eachcomponent (including the amount and nature of the active ingredient(s))and by variation of the lag time, numerous release and plasma profilesmay be obtained. Depending on the duration of the lag time between therelease of the isosorbide dinitrate and hydralazine hydrochloride fromeach component and the nature of the release of the isosorbide dinitrateand hydralazine hydrochloride from each component (i.e. immediaterelease, sustained release etc.), the pulses in the plasma profile maybe well separated and clearly defined peaks (e.g. when the lag time islong) or the pulses may be superimposed to a degree (e.g. in when thelag time is short).

In a preferred embodiment, the controlled release composition accordingto the present invention has an immediate release component and at leastone modified release component, the immediate release componentcomprising a first population of active ingredient containing particlesand the modified release component comprising second and subsequentpopulations of active ingredient containing particles. The second andsubsequent modified release components may comprise a controlled releasecoating. Additionally or alternatively, the second and subsequentmodified release components may comprise a modified release matrixmaterial. In operation, administration of such a multi-particulatemodified release composition having, for example, a single modifiedrelease component results in characteristic pulsatile plasmaconcentration levels of the isosorbide dinitrate and hydralazinehydrochloride in which the immediate release component of thecomposition gives rise to a first peak in the plasma profile and themodified release component gives rise to a second peak in the plasmaprofile. Embodiments of the invention comprising more than one modifiedrelease component give rise to further peaks in the plasma profile.

Such a plasma profile produced from the administration of a singledosage unit is advantageous when it is desirable to deliver two (ormore) pulses of active ingredient without the need for administration oftwo (or more) dosage units. Additionally, in the case of treatingangina, ischaemic heart disease, arterial hypertension and relateddisease conditions, it is particularly useful to have such a bimodalplasma profile. For example, a typical isosorbide dinitrate andhydralazine hydrochloride treatment regime consists of theadministration of two doses of an immediate release dosage formulationgiven twelve hours apart. This type of regime has been found to betherapeutically effective and is widely used. As previously mentioned,the development of patient tolerance is an adverse effect sometimesassociated with isosorbide dinitrate and hydralazine hydrochloridetreatments. It is believed that the trough in the plasma profile betweenthe two peak plasma concentrations is advantageous in reducing thedevelopment of patient tolerance by providing a period of wash out ofthe isosorbide dinitrate and hydralazine hydrochloride active.

In addition, a delivery system having a zero order or pseudo-zero orderdelivery that eliminates or minimizes the “peak” to “trough” ratio isalso described.

Any coating material which modifies the release of the isosorbidedinitrate and hydralazine hydrochloride in the desired manner may beused. In particular, coating materials suitable for use in the practiceof the present invention include but are not limited to polymer coatingmaterials, such as cellulose acetate phthalate, cellulose acetatetrimaletate, hydroxy propyl methylcellulose phthalate, polyvinyl acetatephthalate, ammonio methacrylate copolymers such as those sold under theTrade Mark Eudragit® RS and RL, poly acrylic acid and poly acrylate andmethacrylate copolymers such as those sold under the Trade MarkEudragit® S and L, polyvinyl acetaldiethylamino acetate, hydroxypropylmethylcellulose acetate succinate, shellac; hydrogels and gel-formingmaterials, such as carboxyvinyl polymers, sodium alginate, sodiumcarmellose, calcium carmellose, sodium carboxymethyl starch, polyvinylalcohol, hydroxyethyl cellulose, methyl cellulose, gelatin, starch, andcellulose based cross-linked polymers—in which the degree ofcrosslinking is low so as to facilitate adsorption of water andexpansion of the polymer matrix, hydroxypropyl cellulose, hydroxypropylmethylcellulose, polyvinylpyrrolidone, crosslinked starch,microcrystalline cellulose, chitin, aminoacryl-methacrylate copolymer(Eudragit® RS-PM, Rohm & Haas), pullulan, collagen, casein, agar, gumarabic, sodium carboxymethyl cellulose, (swellable hydrophilic polymers)poly(hydroxyalkyl methacrylate) (m. wt. about 5 k-5,000 k),polyvinylpyrrolidone (m. wt. about 10 k-360 k), anionic and cationichydrogels, polyvinyl alcohol having a low acetate residual, a swellablemixture of agar and carboxymethyl cellulose, copolymers of maleicanhydride and styrene, ethylene, propylene or isobutylene, pectin (m.wt. about 30 k-300 k), polysaccharides such as agar, acacia, karaya,tragacanth, algins and guar, polyacrylamides, Polyox(polyethylene oxides(m. wt. about 100 k-5,000 k), AquaKeep (acrylate polymers, diesters ofpolyglucan, crosslinked polyvinyl alcohol and polyN-vinyl-2-pyrrolidone, sodium starch glucolate (e.g. Explotab (; EdwardMandell C. Ltd.); hydrophilic polymers such as polysaccharides, methylcellulose, sodium or calcium carboxymethyl cellulose, hydroxypropylmethyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, nitrocellulose, carboxymethyl cellulose, cellulose ethers, polyethyleneoxides (e.g. Polyox®, Union Carbide), methyl ethyl cellulose,ethylhydroxy ethylcellulose, cellulose acetate, cellulose butyrate,cellulose propionate, gelatin, collagen, starch, maltodextrin, pullulan,polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl acetate, glycerolfatty acid esters, polyacrylamide, polyacrylic acid, copolymers ofmethacrylic acid or methacrylic acid (e.g. Eudragit®, Rohm and Haas),other acrylic acid derivatives, sorbitan esters, natural gums,lecithins, pectin, alginates, ammonia alginate, sodium, calcium,potassium alginates, propylene glycol alginate, agar, and gums such asarabic, karaya, locust bean, tragacanth, carrageens, guar, xanthan,scleroglucan and mixtures and blends thereof. As will be appreciated bythe person skilled in the art, excipients such as plasticisers,lubricants, solvents and the like may be added to the coating. Suitableplasticisers include for example acetylated monoglycerides; butylphthalyl butyl glycolate; dibutyl tartrate; diethyl phthalate; dimethylphthalate; ethyl phthalyl ethyl glycolate; glycerin; propylene glycol;triacetin; citrate; tripropioin; diacetin; dibutyl phthalate; acetylmonoglyceride; polyethylene glycols; castor oil; triethyl citrate;polyhydric alcohols, glycerol, acetate esters, gylcerol triacetate,acetyl triethyl citrate, dibenzyl phthalate, dihexyl phthalate, butyloctyl phthalate, diisononyl phthalate, butyl octyl phthalate, dioctylazelate, epoxidised tallate, triisoctyl trimellitate, diethylhexylphthalate, di-n-octyl phthalate, di-i-octyl phthalate, di-i-decylphthalate, di-n-undecyl phthalate, di-n-tridecyl phthalate,tri-2-ethylhexyl trimellitate, di-2-ethylhexyl adipate, di-2-ethylhexylsebacate, di-2-ethylhexyl azelate, dibutyl sebacate.

When the modified release component comprises a modified release matrixmaterial, any suitable modified release matrix material or suitablecombination of modified release matrix materials may be used. Suchmaterials are known to those skilled in the art. The term “modifiedrelease matrix material” as used herein includes hydrophilic polymers,hydrophobic polymers and mixtures thereof which are capable of modifyingthe release of isosorbide dinitrate and hydralazine hydrochloridedispersed therein in vitro or in viva Modified release matrix materialssuitable for the practice of the present invention include but are notlimited to microcrystalline cellulose, sodium carboxymethylcellulose,hydroxyalkylcelluloses such as hydroxypropylmethylcellulose andhydroxypropylcellulose, polyethylene oxide, alkylcelluloses such asmethylcellulose and ethylcellulose, polyethylene glycol,polyvinylpyrrolidone, cellulose acteate, cellulose acetate butyrate,cellulose acteate phthalate, cellulose acteate trimellitate,polyvinylacetate phthalate, polyalkylmethacrylates, polyvinyl acetateand mixture thereof.

A controlled release composition according to the present invention maybe incorporated into any suitable dosage form which facilitates releaseof the active ingredient in a pulsatile or zero order manner. Typically,the dosage form may be a blend of the different populations ofisosorbide dinitrate and hydralazine hydrochloride-containing particleswhich make up the immediate release and the modified release components,the blend being filled into suitable capsules, such as hard or softgelatin capsules. Alternatively, the different individual populations ofactive ingredient containing particles may be compressed (optionallywith additional excipients) into mini-tablets which may be subsequentlyfilled into capsules in the appropriate proportions. Another suitabledosage form is that of a multilayer tablet. In this instance the firstcomponent of the controlled release composition may be compressed intoone layer, with the second component being subsequently added as asecond layer of the multilayer tablet. The populations of isosorbidedinitrate and hydralazine hydrochloride-containing particles making upthe composition of the invention may further be included in rapidlydissolving dosage forms such as an effervescent dosage form or afast-melt dosage form.

The composition according to the invention comprises at least twopopulations of isosorbide dinitrate and hydralazinehydrochloride-containing particles which have different in-vitrodissolution profiles.

Preferably, in operation the composition of the invention and the solidoral dosage forms containing the composition release the isosorbidedinitrate and hydralazine hydrochloride such that substantially all ofthe isosorbide dinitrate and hydralazine hydrochloride contained in thefirst component is released prior to release of the isosorbide dinitrateand hydralazine hydrochloride from the second component. When the firstcomponent comprises an immediate release (IR) component, for example, itis preferable that release of the isosorbide dinitrate and hydralazinehydrochloride from the second component is delayed until substantiallyall the isosorbide dinitrate and hydralazine hydrochloride in the IRcomponent has been released. Release of the isosorbide dinitrate andhydralazine hydrochloride from the second component may be delayed asdetailed above by the use of a modified release coating(s) and/or amodified release matrix material.

More preferably, when it is desirable to minimize patient tolerance byproviding a dosage regime which facilitates wash-out of a first dose ofthe isosorbide dinitrate and hydralazine hydrochloride from a patient'ssystem, release of the isosorbide dinitrate and hydralazinehydrochloride from the second and subsequent component is delayed untilsubstantially all of the isosorbide dinitrate and hydralazinehydrochloride contained in the first component has been released, andfurther delayed until at least a portion of the isosorbide dinitrate andhydralazine hydrochloride released from the first component has beencleared from the patient's system. In a preferred embodiment, release ofthe isosorbide dinitrate and hydralazine hydrochloride from the secondcomponent of the composition in operation is substantially, if notcompletely, delayed for a period of at least about two hours afteradministration of the composition.

The isosorbide dinitrate and hydralazine hydrochloride release of thedrug from the second component of the composition in operation issubstantially, if not completely, delayed for a period of at least aboutsix hours, preferably about twelve hours, after administration of thecomposition.

B. Other Types of Controlled Release Isosorbide Dinitrate andHydralazine Hydrochloride Compositions

As described herein, the invention includes various types of controlledrelease systems by which the active drug may be delivered in a pulsatileor zero order manner. These systems include, but are not limited to:films with the drug in a polymer matrix (monolithic devices); the drugcontained by the polymer (reservoir devices); polymeric colloidalparticles or microencapsulates (microparticles, microspheres ornanoparticles) in the form of reservoir and matrix devices; drugcontained by a polymer containing a hydrophilic and/or leachableadditive e.g., a second polymer, surfactant or plasticizer, etc. to givea porous device, or a device in which the drug release may beosmotically “controlled” (both reservoir and matrix devices); entericcoatings (ionizable and dissolve at a suitable pH); (soluble) polymerswith (covalently) attached ‘pendant’ drug molecules; devices whererelease rate is controlled dynamically: e.g., the osmotic pump.

The delivery mechanism of the present invention will control the rate ofrelease of the drug. While some mechanisms will release the drug at aconstant rate (zero order), others will vary as a function of timedepending on factors such as changing concentration gradients oradditive leaching leading to porosity, etc.

Polymers used in sustained release coatings are necessarilybiocompatible, and ideally biodegradable. Examples of both naturallyoccurring polymers such as Aquacoat® (FMC Corporation, Food &Pharmaceutical Products Division, Philadelphia, USA) (ethylcellulosemechanically spheronised to sub-micron sized, aqueous based,pseudo-latex dispersions), and also synthetic polymers such as theEudragit® (Röhm Pharma, Weiterstadt) range of poly(acrylate,methacrylate) copolymers are known in the art.

1. Reservoir Devices

A typical approach to controlled release is to encapsulate or containthe drug entirely (e.g., as a core), within a polymer film or coat(i.e., microcapsules or spray/pan coated cores).

The various factors that can affect the diffusion process may readily beapplied to reservoir devices (e.g., the effects of additives, polymerfunctionality {and, hence, sink-solution pH} porosity, film castingconditions, etc.) and, hence, the choice of polymer must be an importantconsideration in the development of reservoir devices. Modeling therelease characteristics of reservoir devices (and monolithic devices) inwhich the transport of the drug is by a solution-diffusion mechanismtherefore typically involves a solution to Fick's second law(unsteady-state conditions; concentration dependent flux) for therelevant boundary conditions. When the device contains dissolved activeagent, the rate of release decreases exponentially with time as theconcentration (activity) of the agent (i.e., the driving force forrelease) within the device decreases (i.e., first order release). If,however, the active agent is in a saturated suspension, then the drivingforce for release is kept constant (zero order) until the device is nolonger saturated. Alternatively the release-rate kinetics may bedesorption controlled, and a function of the square root of time.

Transport properties of coated tablets, may be enhanced compared tofree-polymer films, due to the enclosed nature of the tablet core(permeant) which may enable the internal build-up of an osmotic pressurewhich will then act to force the permeant out of the tablet.

The effect of de-ionized water on salt containing tablets coated inpoly(ethylene glycol) (PEG)-containing silicone elastomer, and also theeffects of water on free films has been investigated. The release ofsalt from the tablets was found to be a mixture of diffusion throughwater filled pores, formed by hydration of the coating, and osmoticpumping. KCl transport through films containing just 10% PEG wasnegligible, despite extensive swelling observed in similar free films,indicating that porosity was necessary for the release of the KCl whichthen occurred by ‘trans-pore diffusion.’ Coated salt tablets, shaped asdisks, were found to swell in de-ionized water and change shape to anoblate spheroid as a result of the build-up of internal hydrostaticpressure: the change in shape providing a means to measure the ‘force’generated. As might be expected, the osmotic force decreased withincreasing levels of PEG content. The lower PEG levels allowed water tobe imbibed through the hydrated polymer; whilst the porosity resultingfrom the coating dissolving at higher levels of PEG content (about 20 toabout 40%) allow the pressure to be relieved by the flow of KCl.

Methods and equations have been developed, which by monitoring(independently) the release of two different salts (e.g., KCl and NaCl)allowed the calculation of the relative magnitudes that both osmoticpumping and trans-pore diffusion contributed to the release of salt fromthe tablet. At low PEG levels, osmotic flow was increased to a greaterextent than was trans-pore diffusion due to the generation of only a lowpore number density: at a loading of 20%, both mechanisms contributedapproximately equally to the release. The build-up of hydrostaticpressure, however, decreased the osmotic inflow, and osmotic pumping. Athigher loadings of PEG, the hydrated film was more porous and lessresistant to outflow of salt. Hence, although the osmotic pumpingincreased (compared to the lower loading), trans-pore diffusion was thedominant release mechanism. An osmotic release mechanism has also beenreported for microcapsules containing a water soluble core.

2. Monolithic Devices (Matrix Devices)

Monolithic (matrix) devices are possibly the most common of the devicesfor controlling the release of drugs. This is possibly because they arerelatively easy to fabricate, compared to reservoir devices, and thereis not the danger of an accidental high dosage that could result fromthe rupture of the membrane of a reservoir device. In such a device theactive agent is present as a dispersion within the polymer matrix, andthey are typically formed by the compression of a polymer/drug mixtureor by dissolution or melting. The dosage release properties ofmonolithic devices may be dependent upon the solubility of the drug inthe polymer matrix or, in the case of porous matrixes, the solubility inthe sink solution within the particle's pore network, and also thetortuosity of the network (to a greater extent than the permeability ofthe film), dependent on whether the drug is dispersed in the polymer ordissolved in the polymer. For low loadings of drug, (0 to 5% W/V) thedrug will be released by a solution-diffusion mechanism (in the absenceof pores). At higher loadings (5 to 10% W/V), the release mechanism willbe complicated by the presence of cavities formed near the surface ofthe device as the drug is lost: such cavities fill with fluid from theenvironment increasing the rate of release of the drug.

It is common to add a plasticiser (e.g., a poly(ethylene glycol)), asurfactant, or adjuvant (i.e., an ingredient which increaseseffectiveness), to matrix devices (and reservoir devices) as a means toenhance the permeability (although, in contrast, plasticizers may befugitive, and simply serve to aid film formation and, hence, decreasepermeability—a property normally more desirable in polymer paintcoatings). It was noted that the leaching of PEG increased thepermeability of (ethyl cellulose) films linearly as a function of PEGloading by increasing the porosity, however, the films retained theirbarrier properties, not permitting the transport of electrolyte. It wasdeduced that the enhancement of their permeability was as a result ofthe effective decrease in thickness caused by the PEG leaching. This wasevidenced from plots of the cumulative perminant flux per unit area as afunction of time and film reciprocal thickness at a PEG loading of 50%W/W: plots showing a linear relationship between the rate of permeationand reciprocal film thickness, as expected for a (Fickian)solution-diffusion type transport mechanism in a homogeneous membrane.Extrapolation of the linear regions of the graphs to the time axis gavepositive intercepts on the time axis: the magnitude of which decreasedtowards zero with decreasing film thickness. These changing lag timeswere attributed to the occurrence of two diffusional flows during theearly stages of the experiment (the flow of the ‘drug’ and also the flowof the PEG), and also to the more usual lag time during which theconcentration of permeant in the film is building-up. Caffeine, whenused as a permeant, showed negative lag times. No explanation of thiswas forthcoming, but it was noted that caffeine exhibited a lowpartition coefficient in the system, and that this was also a feature ofaniline permeation through polyethylene films which showed a similarnegative time lag.

The effects of added surfactants on (hydrophobic) matrix devices hasbeen investigated. It was thought that surfactant may increase the drugrelease rate by three possible mechanisms: (i) increased solubilization,(ii) improved ‘wettability’ to the dissolution media, and (iii) poreformation as a result of surfactant leaching. For the system studied(Eudragit® RL 100 and RS 100 plasticised by sorbitol, Flurbiprofen asthe drug, and a range of surfactants) it was concluded that improvedwetting of the tablet led to only a partial improvement in drug release(implying that the release was diffusion, rather than dissolution,controlled), although the effect was greater for Eudragit® RS thanEudragit® RL, whilst the greatest influence on release was by thosesurfactants that were more soluble due to the formation of ‘disruptions’in the matrix allowing the dissolution medium access to within thematrix. This is of obvious relevance to a study of latex films whichmight be suitable for pharmaceutical coatings, due to the ease withwhich a polymer latex may be prepared with surfactant as opposed tosurfactant-free. Differences were found between the two polymers—withonly the Eudragit® RS showing interactions between the anionic/cationicsurfactant and drug. This was ascribed to the differing levels ofquaternary ammonium ions on the polymer.

Composite devices consisting of a polymer/drug matrix coated in apolymer containing no drug also exist. Such a device was constructedfrom aqueous Eudragit® latices, and was found to give zero order releaseby diffusion of the drug from the core through the shell. Similarly, apolymer core containing the drug has been produced, but coated this witha shell that was eroded by the gastric fluid. The rate of release of thedrug was found to be relatively linear (a function of the rate limitingdiffusion process through the shell) and inversely proportional to theshell thickness, whereas the release from the core alone was found todecrease with time.

3. Microspheres

Methods for the preparation of hollow microspheres (‘microballoons’)with the drug dispersed in the sphere's shell, and also highly porousmatrix-type microspheres (‘microsponges’) have been described. Themicrosponges were prepared by dissolving the drug and polymer inethanol. On addition to water, the ethanol diffused from the emulsiondroplets to leave a highly porous particle.

The hollow microspheres were formed by preparing a solution ofethanol/dichloro-methane containing the drug and polymer. On pouringinto water, this formed an emulsion containing the dispersedpolymer/drug/solvent particles, by a coacervation-type process, fromwhich the ethanol (a good solvent for the polymer) rapidly diffusedprecipitating polymer at the surface of the droplet to give ahard-shelled particle enclosing the drug, dissolved in thedichloromethane. At this point, a gas phase of dichloromethane wasgenerated within the particle which, after diffusing through the shell,was observed to bubble to the surface of the aqueous phase. The hollowsphere, at reduced pressure, then filled with water, which could beremoved by a period of drying. (No drug was found in the water.) Asuggested use of the microspheres was as floating drug delivery devicesfor use in the stomach.

4. Pendent Devices

A means of attaching a range of drugs such as analgesics andantidepressants, etc., by means of an ester linkage to poly(acrylate)ester latex particles prepared by aqueous emulsion polymerization hasbeen developed. These latices when passed through an ion exchange resinsuch that the polymer end groups were converted to their strong acidform could ‘self-catalyse’ the release of the drug by hydrolysis of theester link.

Drugs have been attached to polymers, and also monomers have beensynthesized with a pendent drug attached. The research group have alsoprepared their own dosage forms in which the drug is bound to abiocompatible polymer by a labile chemical bond polyanhydrides preparedfrom a substituted anhydride (itself prepared by reacting an acidchloride with the drug: methacryloyl chloride and the sodium salt ofmethoxy benzoic acid) were used to form a matrix with a second polymer(Eudragit® RL) which released the drug on hydrolysis in gastric fluid.The use of polymeric Schiff bases suitable for use as carriers ofpharmaceutical amines has also been described.

5. Enteric Films

Enteric coatings consist of pH sensitive polymers. Typically thepolymers are carboxylated and interact (swell) very little with water atlow pH, whilst at high pH the polymers ionize causing swelling, ordissolving of the polymer. Coatings can therefore be designed to remainintact in the acidic environment of the stomach (protecting either thedrug from this environment or the stomach from the drug), but todissolve in the more alkaline environment of the intestine.

6. Osmotically Controlled Devices

The osmotic pump is similar to a reservoir device but contains anosmotic agent (eg, the active agent in salt form) which acts to imbibewater from the surrounding medium via a semi-permeable membrane. Such adevice, called the ‘elementary osmotic pump’, has been described.Pressure is generated within the device which forces the active agentout of the device via an orifice (of a size designed to minimize solutediffusion, whilst preventing the build-up of a hydrostatic pressure headwhich has the effect of decreasing the osmotic pressure and changing thedimensions {volume} of the device). Whilst the internal volume of thedevice remains constant, and there is an excess of solid (saturatedsolution) in the device, then the release rate remains constantdelivering a volume equal to the volume of solvent uptake.

7. Electrically Stimulated Release Devices

Monolithic devices have been prepared using polyelectrolyte gels whichswelled when, for example, an external electrical stimulus was applied,causing a change in pH. The release could be modulated, by the current,giving a pulsatile release profile.

8. Hydrogels

Hydrogels find a use in a number of biomedical applications, in additionto their use in drug matrices (e.g., soft contact lenses, and various‘soft’ implants, etc.).

C. Methods of Using Controlled Release Isosorbide Dinitrate andHydralazine Hydrochloride Compositions

The present invention further provides a method of treating a patientsuffering from angina, ischaemic heart disease, arterial hypertensionand related disease conditions utilizing an isosorbide dinitrate andhydralazine hydrochloride composition of the present inventioncomprising the administration of a therapeutically effective amount of asolid oral dosage form of isosorbide dinitrate and hydralazinehydrochloride to provide a pulsed or multi-modal or zero order deliveryof the isosorbide dinitrate and hydralazine hydrochloride. Advantages ofthe present invention include reducing the dosing frequency required byconventional multiple IR dosage regimes while still maintaining thebenefits derived from a pulsatile plasma profile or eliminating orminimizing the “peak” to “trough” ratio. This reduced dosing frequencyis advantageous in terms of patient compliance to have a formulationwhich may be administered at reduced frequency. The reduction in dosagefrequency made possible by utilizing the present invention wouldcontribute to reducing health care costs by reducing the amount of timespent by health care workers on the administration of drugs.

In the following examples, all percentages are weight by weight unlessotherwise stated. The term “purified water” as used throughout theExamples refers to water that has been purified by passing it through awater filtration system. It is to be understood that the examples arefor illustrative purposes only, and should not be interpreted asrestricting the spirit and breadth of the invention, as defined by thescope of the claims that follow.

Example 1 Multiparticulate Modified Release Composition ContainingIsosorbide Dinitrate and Hydralazine Hydrochloride

A multiparticulate modified release composition according to the presentinvention comprising an immediate release component and a modifiedrelease component containing isosorbide dinitrate and hydralazinehydrochloride is prepared as follows.

(a) Immediate Release Component.

A powder blend of isosorbide dinitrate or hydralazine hydrochloride isprepared according to any of the formulations given in Table 1.

A binder solution is prepared according to any of the formulations givenin Table 2.A protective coating solution is prepared according to any of theformulations given in Table 3.

The powder blend is then layered onto a suitable substrate (e.g. sugarspheres or microcrystalline cellulose pellets) using a suitable bindersolution to a level of approximately 400% solids weight gain using, forexample, a Vector Granurex GX-40 (Vector Corporation, IA) rotarygranulator apparatus to form the IR particles of the immediate releasecomponent. After the powder layering process is complete, the protectivecoating solution is coated onto the immediate release beads to a levelof approximately 3% protective compound based on the mass of immediaterelease beads to be coated. A glidant powder blend consisting of talc,silicon dioxide or a combination of the two is simultaneously appliedeither separately or by suspension in the coating solution to reducesticking and static. Examples of the final compositions of the immediaterelease beads are shown in Table 4.

TABLE 1 Powder blend compositions Amount Amount Amount Ingredient (mg/g)(mg/g) (mg/g) Diluted isosorbide dinitrate — — 980 (40:60mannitol/lactose) Hydralazine hydrochloride 980 800 — Talc  10  10  10Silicon dioxide  10  10  10 Fumaric acid — 180 —

TABLE 2 Binder solution compositions Ingredient Amount (mg/g) Amount(mg/g) Isopropanol 900 883.4 Povidone 100 100 Edetate disodium — 16.6

TABLE 3 Protective coating solution compositions Ingredient Amount(mg/g) Isopropanol 937.5 Basic butylated methacrylate copolymers 62.5

TABLE 4 Immediate release component compositions Amount Amount AmountAmount Ingredient (mg/g) (mg/g) (mg/g) (mg/g) Povidone 56.6 56.6 56.656.6 Edetate disodium — 9.4 — 9.4 Isosorbide dinitrate — — 273.7 270.0Mannitol/Lactose — — 410.5 405.0 Hydralazine hydrochloride 684.2 551.0 —— Talc 21.1 21.0 21.1 21.0 Silicon dioxide 21.1 21.0 21.1 21.0 Fumaricacid — 124.0 — — Basic butylated methacrylate 28.3 28.3 28.3 28.3copolymers Sugar spheres (30/35 mesh) 188.7 188.7 188.7 188.7

(b) Modified Release Components

Isosorbide dinitrate and hydralazine hydrochloride containing delayedrelease particles are prepared by coating immediate release particlesprepared according to Example 1(a) above with a modified release coatingsolution as detailed in Table 5. Talc is simultaneously applied duringcoating as a glidant and anti-static agent. The immediate releaseparticles are coated to varying levels up to approximately 30% polymerweight gain using, for example, a rotary granulator or fluid bedapparatus. Example compositions of the modified release componentsrepresenting 20% polymer weight gain are shown in Table 6.

TABLE 5 Modified release component coating solutions Ingredient Amount(mg/g) Isopropanol 856 Water 24 Methacrylic acid copolymers 100 Triethylcitrate 20

TABLE 6 Modified release component compositions Amount Amount AmountAmount Ingredient (mg/g) (mg/g) (mg/g) (mg/g) Povidone 39.3 39.3 39.339.3 Edetate, disodium — 6.5 — 6.5 Isosorbide dinitrate — — 190.0 187.5Mannitol/Lactose — — 285.1 281.2 Hydralazine hydrochloride 475.1 382.6 —— Talc 153.6 153.5 153.6 153.5 Silicon dioxide 14.7 14.6 14.7 14.6Fumaric acid — 86.1 — — Basic butylated methacrylate 19.7 19.7 19.7 19.7copolymers Sugar spheres (30/35 mesh) 131.0 131.0 131.0 131.0Methacrylic acid copolymers 138.9 138.9 138.9 138.9 Triethyl Citrate,USP 27.8 27.8 27.8 27.8

(c) Encapsulation of Immediate and Delayed Release Particles.

The immediate and delayed release particles prepared according toExample 1(a) and (b) above are blended and encapsulated in size 0 hardgelatin capsules to an overall dosage strength of 60/112.5 mg ofisosorbide dinitrate and hydralazine hydrochloride, respectively, using,for example, a Bosch GKF 400S encapsulation apparatus. The overalldosage strength of 60/112.5 mg isosorbide dinitrate and hydralazinehydrochloride, is made up of 40/75 mg from the immediate releasecomponent and 20/37.5 mg from the modified release component.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the methods and compositionsof the present inventions without departing from the spirit or scope ofthe invention. Thus, it is intended that the present invention cover themodification and variations of the invention provided they come withinthe scope of the appended claims and their equivalents.

1. A controlled release pharmaceutical composition comprising apopulation of isosorbide dinitrate and hydralazine, or a salt orderivative thereof, -containing particles, wherein at least a portion ofthe particles incorporate a modified-release coating or, alternativelyor additionally, a modified-release matrix material, such that thecomposition following oral delivery to a subject delivers the isosorbidedinitrate and hydralazine, or salt or derivative thereof, in a pulsatileor zero order manner.
 2. The composition according to claim 1, whereinthe population of either isosorbide dinitrate or hydralazine particles,or both, have a protective coating.
 3. The composition according toclaim 2, wherein the protective coating material is selected from thegroup comprising hydrophilic polymers, hydrophobic polymers, naturalpolymers, synthetic polymers and mixtures thereof.
 4. The compositionaccording to claim 1, wherein the population of isosorbide dinitrate andhydralazine particles comprises modified-release particles.
 5. Thecomposition according to claim 1, wherein the population of particles isan erodable formulation.
 6. The composition according to claim 4,wherein said modified-release particles have a modified-release coating.7. The composition according to claim 4, wherein said modified-releaseparticles comprise a modified-release matrix coating.
 8. The compositionof claim 1 wherein said modified-release coating and/or saidmodified-release matrix material is selected from the group consistingof hydrophilic polymers, hydrophobic polymers, natural polymers,synthetic polymers and mixtures thereof.
 9. The composition of claim 8wherein said particles incorporating a modified-release coating and/or amodified-release matrix material are combined so that said isosorbidedinitrate and hydralazine are released by erosion to the surroundingenvironment.
 10. The composition according to claim 8, wherein at leastone portion of the composition further comprises an enhancer.
 11. Thecomposition according to claim 8, wherein the amount of isosorbidedinitrate and hydralazine contained therein is in an amount, each, offrom about 0.1 mg to about 1 g.
 12. The dosage form according to claim11 comprising a blend of the particles contained in a hard gelatin orsoft gelatin capsule.
 13. The dosage form according to claim 12, whereinthe particles are in the form of mini-tablets and the capsule contains amixture of the mini-tablets.
 14. The dosage form according to claim 13,in the form of a tablet comprising a layer of compressed isosorbidedinitrate and hydralazine-containing particles.
 15. The dosage formaccording to claim 14, wherein the isosorbide dinitrate andhydralazine-containing particles are provided in a rapidly dissolvingdosage form.
 16. A method for the treatment of angina, ischaemic heartdisease, arterial hypertension or related disease conditions comprisingadministering a therapeutically effective amount of a compositionaccording to claim
 1. 17. A method for the treatment of angina,ischaemic heart disease, arterial hypertension or related diseaseconditions comprising administering a therapeutically effective amountof a composition according to claim
 2. 18. The composition according toclaim 1, wherein the particles incorporating a modified-release coatingcomprise a pH-dependent polymer coating which is effective in releasinga pulse of the active ingredient following a time delay of two to twelvehours.
 19. The composition according to claim 18, wherein the polymercoating comprises methacrylate copolymers.
 20. The composition accordingto claim 1, wherein the modified-release coating comprises a mixture ofmethacrylate and ammonio methacrylate copolymers in a ratio sufficientto achieve a pulse of the active ingredient following a time delay. 21.The composition according to claim 20, wherein the ratio of methacrylateto ammonio methacrylate copolymers is between approximately 95:5 and50:50.
 23. The composition according to claim 1, wherein the hydralazinecomprises hydralazine hydrochloride.
 23. The composition according toclaims 1, wherein at least one portion of the composition furthercomprises an antioxidant.
 24. The composition according to claim 1,wherein at least one portion of the composition further comprises achelating agent.
 25. The composition according to claim 23 wherein theantioxidant comprises ascorbic acid or a salt or derivative thereof. 26.The composition according to claim 24, wherein the chelating agentcomprises edetic acid or a salt or derivative thereof.
 27. Thecomposition according to claim 24, wherein the chelating agent comprisescitric acid or fumaric acid or any salts or derivatives thereof.
 28. Thecomposition according to claim 1, wherein at least one portion of thecomposition further comprises sugar spheres.
 29. The compositionaccording to claim 1, wherein at least one portion of the compositionfurther comprises microcrystalline cellulose pellets.
 30. The dosageform according to claim 14, wherein the hydralazine compriseshydralazine hydrochloride.
 31. The dosage form according to claim 14,wherein the isosorbide dinitrate comprises isosorbide dinitrate or anyactive metabolites thereof.
 32. The method according to claim 16,wherein the hydralazine comprises hydralazine hydrochloride.
 33. Themethod according to claim 16, wherein the isosorbide dinitrate comprisesisosorbide dinitrate or any active metabolites thereof.